The present invention relates to a method for preventing coloration of an organosilicon compound or, more particularly, to a method for preventing coloration of an organosilicon compound even at an elevated temperature or under intense light so that the organosilicon compound thus prevented from coloration is useful as an additive to or as a treatment agent of a white or colorless material such as fillers, fibers, resins and the like.
It is a trend in recent years that organosilicon compounds such as organosilanes and organopolysiloxanes are modified by introducing various kinds of functional groups into the molecular structure so as to impart the compound with improved compatibility or reactivity with various kinds of fillers, fibers, resins and the like for which the organosilicon compound is an additive or a treatment agent. When the organosilicon compound is an organopolysiloxane, it has a structure represented, for example, by the general formula EQU Q--(--SiMe.sub.2 --O--).sub.m --(--SiMeQ--O--).sub.n --SiMe.sub.2 --Q,
in which Me is a methyl group, each Q is, independently from the others, a monovalent hydrocarbon group or a functional organic group such as alkoxy, acyloxy, (meth)acryloxyalkyl, aminoalkyl, glycidyloxyalkyl, halogenoalkyl, mercaptoalkyl, amidoalkyl and polyoxyalkylene-containing alkyl groups, at least one of the groups denoted by Q being such a functional organic group, and the subscripts m and n are each zero or a positive integer with the proviso that m+n is not zero. When the organosilane compound is an organosilane, it is represented by the general formula EQU R.sup.1.sub.3-p R.sup.2 SiMe.sub.p,
in which R.sup.1 is a hydrolyzable group such as alkoxy, acyloxy and amino groups, R.sup.2 is an organic group including alkyl, alkenyl, (meth)acryloxy, amino, amido, urea, epoxy, amino hydrochloride, halogenoalkyl, mercapto and polyoxyalkylene groups and p is 0, 1 or 2.
One of the problems in the use of these functional organosilicon compounds is that the compound is sometimes colored due to the content of a small amount of coloring impurities entering the compound in the course of the synthetic preparation of the compound or as a result of the reaction taking place in the modifying functional groups at an elevated temperature or under exposure to intense light. Once the organosilicon compound is colored, it follows that the material admixed or treated with such a colored organosilicon compound is also colored resulting in a great decrease in the commercial value of the product. Nevertheless, no very effective method is known for preventing coloration of an organosilicon compound.
This problem is particularly serious when the functional group is an aminoalkyl group, which is optionally in the form of a salt with an inorganic halogen-containing acid, or a methacryloxyalkyl group since these groups are liable to be decomposed under the influences of heat and light. In this regard, coloration of an organosilicon compound may be caused when the compound is synthesized in a process in which an amino compound or a hydrochloride is involved as an auxiliary reactant or a product derived therefrom.